Tuesday, July 2, 2013

Understanding Aquarium Water pH

What is pH?

Are you aware that maintaining the pH of aquarium water is still a factor of continuous concern even to veteran aquarists?

pH expresses the degree of acidity or alkalinity and is measured on a logarithmic scale where 7 is neutral. Values below 7 indicate different levels of acidity with pH 0 considered as extremely acidic. On the other hand, values higher than 7 denote various levels of alkalinity with pH 15 classified as extremely alkaline.

In Chemistry we were taught to understand that pH reflects the proportion of hydrogen ions (H+) to hydroxide ions (OH-) in a solution. As you can see from the figure below, the more hydrogen ions (H+) that are present in a solution, the more acidic the solution will be. With equal amounts of H+ and OH- in a solution, the pH will be will neutral. An alkaline condition is achieved when there is more OH- than H+ present in the solution. For fish aquarium tanks and ponds, water testing kits can help keep track of the water’s pH and indicate if it is within desired levels or if there is a need for you to increase or decrease the pH to ideal levels.

pH Scale

Factors that Influence Water pH

Water pH can easily be influenced by the type of minerals and gases which are dissolved in it. Typically, the pH of groundwater ranges from 6-8.5 while surface waters range from 6.5-8.5. Water is said to be “soft” when the pH is less than 6.5 while water with pH higher than 8.5 is considered “hard”.

Water (H20) is considered to be neutral at 25° C with a pH very close to 7. Its chemical formula, H2O, means that a hydrogen ion (H+) which has a positive charge is bonded with a hydroxide ion (OH-) which is negatively charged. This simply means that water possesses properties of both an acid and a base.

What happens when there is a rise and fall in aquarium water pH?

When we say that the pH scale is logarithmic, we simply mean that a one unit shift is equal to a 10-fold increase in the H+ concentration in the solution. For example, a pH 4 solution is 10 times more acidic than pH 5, and 100 times more acidic than pH 6. When you think about it, these logarithmic values of pH can have a profound effect on aquarium life. Even a small rise or fall in the tank’s water pH can actually result in a drastic change in the aquatic environment that can exert an unfavourable effect on your fishes!

When you are raising specific fish species, monitoring pH and other factors affecting water quality in aquarium tanks is a basic regimen for aquarists. You can accomplish this by using water quality testing kits which you can conveniently order from an online aquarium store.

Generally, most species of fish can thrive well in a wide range of water pH, although once you read more about the particular fish that you are keeping, you will find that they indeed have IDEAL pH requirements. Most exotic fishes are more particular about the pH that they require compared to native fish species. Water pH is also an important parameter to consider when you choose to breed fish.


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